Printed circuit spark gap protector for cathode ray tube

ABSTRACT

A thin, flexible arc discharge device for prevention of arc discharge of a CRT capacitance through the driver circuits.

United States Patent Kleen Aug. 8, 1972 PRINTED CIRCUIT SPARK GAP PROTECTOR FOR CATHODE RAY TUBE Inventor: Bergert G. Kleen, Kingston, NY.

International Business Machines Corporation, Armonk, NY.

Filed: April 30, 1970 Appl. No.: 33,410

Assignee:

US. Cl. ..313/318, 313/325, 313/313,

339/193 Int. Cl. ..H01j 5/54, l-IOlj 5/56, HOlr l3/46 Field of Search ..315/1;313/3l8, 325

[56] References Cited UNITED STATES PATENTS 3,377,612 4/1968 Klier e1: al. .3l3/3l8 X 3,502,933 3/1970 Leimontas et al. ..3 l 3/325 Primary ExaminerRobert Segal Attorney-Hanifin and Jancin and George E. Clark [57] ABSTRACT A thin, flexible arc discharge device for prevention of arc discharge of a CRT capacitance through the driver circuits.

2 Claims, 3 Drawing Figures PATENIED AUG 8 I972 FIG.2

INVENTOR BERGERT G. KLEEN M AGENT BACKGROUND OF THE INVENTION This invention relates to are discharge devices and more particularly to are discharge devices for discharging the capacitance of a cathode ray tube.

Due to the structure of cathode ray tubes and the high potential applied to the anode, arcdischarge occasionally occurs between points of high potential and points of low potential or ground within the tube. This high potential is conducted through the pins at the base of the CRT and can cause damage to the driving circuitry.

In the prior art, tube sockets have been developed to provide means for discharging the high potential to reduce possibility of damage to the driving circuitry. However, the prior art devices use a molded grounding ring which fits over the pins of the cathode ray tube and which, because of the thickness of the grounding ring, require extension of the CRT pins to provide proper seating in the socket.

Therefore, it is an object of the instant invention to eliminate arc discharge to the driving circuits of a cathode ray tube system by means of a thin, flexible arc discharge device.

It is a further object of this invention to discharge the capacitance in a cathode ray tube by means of an inexpensive, flexible arc discharge device mountable over the base pins of a cathode ray tube.

It is a still further object of this invention to discharge the capacitance of a cathode ray tube using a device in which contact is made on one surface'thereof between the pins of a cathode ray tube and a first printed circuit and on a second surface thereof, between a ground or low potential point and a second printed circuit.

SUMMARY A print circuit pattern is applied to a thin, flexible, non-conducting base material, such as polyethylene terephthalate, in a configuration which matches the pin configuration of a CRT base which is to be protected. The gap distances are selected according to the nominal operating voltage of the pin to be protected with proper allowance for air pressure and humidity of the environment. The printed circuit is coated with a conductive material and the pinholes are punched to provide an interference fit. The thin base material will allow the printed circuits to conform to the pin diameter and spacing irregularities. The return electrode is connected to the nearest available grounding point.

The foregoing and other objects, features and advantages of the invention will be apparent from the following, more particular description of the preferred embodiment of the invention, as illustrated in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows a front view of an arc discharge device embodying the invention.

FIG. 2 shows a rear view of an arc discharge device embodying the invention.

FIG. 3 is a side view showing the arc discharge device in place mounted over the pins of a cathode ray tube.

2 DESCRIPTION OF THE INVENTION Referring now to FIGS. 1 and 2, an arc discharge device embodying the invention will be described in more detail.

An arc discharge device pin is constructed having a base 11 which is a thin, flexible, non-conducting material, such as polyethylene terephthalate. A layer of conducting material such as copper is applied to both the front and rear surfaces of the base material.

The printed circuit pattern is then formed which produces annular conducting ring 13 and CRT pin contacts 14 with interference fit holes 15 therein. The contacts 14 being spaced from the annular ring .13 by a small insulating gap 17. The dimension of the insulating gap 17 is designed so that no arcing will occur under normal operating potentials at the pin, but anode potential arcing will jump the gap and pass to ground.

The arc discharge device 10 also includes a tail electrode 16 which is connected to the nearest ground point. Space 18 with keyway 19 are positionedsuch that the arc discharge device will mount on the base of a cathode ray tube with the proper orientation of the pin contacts with the pins to be protected.

Referring now to FIG. 3, a cathode ray tube neck 20 is shown with a base 22 mounted thereon having pins 25 extending therefrom. The are discharge device is mounted on pins 25 such that tail electrode 16 is free to be connected to a nearby ground point.

I OPERATION The are discharge device embodying the invention is constructed so that gaps 17 are large enough to prevent arc-over. under normal voltage operation of the pin protected yet small enough topass a. current between the pins 25 and the annular grounding ring 13 where an internal arc has occurred resulting in the anode potential, high voltage being applied to one of the base pins 25. Typically, the dimension for gap 17 is in the range of I 0.012 to 0.018 inches.

While the invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. An arc discharge device comprising in combination a cathode ray tube having a plurality of pins on the base thereof; and

a flexible insulating base,

said flexible insulating base having a printed circuit pattern thereon,

a printedcircuit pattern on said insulating base, said printed circuit pattern including a common conducting element and a plurality of contacts uniformly spaced therefrom, said plurality fitting tightly over the pins of said cathode ray tube, said corrunon conducting element and each of said plurality of contacts being so spaced as to discharge through said common conducting element when the potential thereacross exceeds a critical level;

said common conducting element having an appendage adapted for connection to a source of reference potential to complete a capacitance discharge return circuit; and

a keyed opening in said flexible insulating base for orientation of said device with respect to said plurality of pins on the base of said cathode ray tube, whereby a tube socket may be inserted on said pins over said flexible insulating base.

2. A device of the type claimed in claim 1 wherein 

1. An arc discharge device comprising in combination a cathode ray tube having a plurality of pins on the base thereof; and a flexible insulating base, said flexible insulating base having a printed circuit pattern thereon, a printed circuit pattern on said insulating base, said printed circuit pattern including a common conducting element and a plurality of contacts uniformly spaced therefrom, said plurality fitting tightly over the pins of said cathode ray tube, said common conducting element and each of said plurality of contacts being so spaced as to discharge through said common conducting element when the potential thereacross exceeds a critical level; said common conducting element having an appendage adapted for connection to a source of reference potential to complete a capacitance discharge return circuit; and a keyed opening in said flexible insulating base for orientation of said device with respect to said plurality of pins on the base of said cathode ray tube, whereby a tube socket may be inserted on said pins over said flexible insulating base.
 2. A device of the type claimed in claim 1 wherein said arc discharge device is adapted to discharge the capacitance of said cathode ray tube when the high anode potential of said cathode ray tube is applied to one of said plurality of contacts through said associated pins on said cathode ray tube. 